Radio frequency (RF) receivers (RX) are well-known in the electrical art. Integrated RF receivers are typically zero-IF or low-IF (i.e. homodyne) because of the well-known benefits, including a high-level of integration, the ability to use low-pass filtering for channel selection and the avoidance of an external IF band-pass filter (BPF). Weak desired signals are typically accompanied by large blocking interferers. These blockers can dramatically degrade the receiver performance by causing gain compression and higher-order nonlinearities as well as increasing noise figure (NF) of the receiver. Conventionally, these out-of-band blockers are filtered out by a bulky and expensive SAW filter placed before the input to the low noise amplifier (LNA). Since the desired RF signal could be weak and the dynamic range requirements of a given specification must be met, the gain of the LNA should be kept high and the blockers should be filtered out. Otherwise, the mixer and the following stages could get saturated. SAW-less receivers are known in the art. Prior art SAW-less receivers are based on a homodyne architecture. Unfortunately, they all exhibit well-known homodyne RX issues such as sensitivity to 1/f noise and varying dc offsets, finite IIP2, all of which get worse with the inevitable scaling of the process technology.
There is thus a need for a SAW-less receiver architecture that is highly integrated, does not suffer from the disadvantages of prior art receivers and effectively filters blocking interferer signals.